Question

studying for the SAT. If I disagree with an answer or still don't understand why it is wrong, I will post here. I have 2 questions so far.

Answer 1

@Shadow

Answer 2

If -4<=x<=2 and y=1-x^2, what number is obtained when the smallest possible value of y is subtracted from the largest possible value of y^2?

Answer 3

the answer is 16. I have 15. Can y not=0?

Answer 4

1. how many will be the smallest possible value of y ?

Answer 5

-4 is less than 0 tho

Answer 6

2. how many will be the largest possible value of y^2 ?

Answer 7

x=[-4,2] ,yes ?

Answer 8

how you get the smallest possible value of y ?

Answer 9

@ThisGirlPretty do you understand it now ?

Answer 10

okay do y'all not see the problem above
so 1-4^2=15
-4 is the value of x
1-1^2=0
15-0=15
you have to solve the equation for y and subtract both y's but I don't agree with the SAT book being 16 and not 15 because even if you did 0 instead of 1
15-1=14 so idk

Answer 11

please answer my above wrote question - how many will be the smalest possible value of y ?

Answer 12

for x=2 you get the smallest possible value of y

y = 1-2^2

y = 1 -4

y = -3

yes ?

Answer 13

2. how many will be the largest possible value of y^2 ?

Answer 14

that's what they are looking for
a square root has 2 answers a negative and a positive
the negative is for example -2*-2 which is 4
everything in here is as if it was in parentheses
every positive number has 2 square roots so although I get what you are trying to get at but it is taught that unlike otherwise stated it is a positive number so that's how I have to do the math to get the right answer and if that is how the sat works, then I must do it that way to get the best score

Answer 15

I understand now. 1-16=-15 1-0^2=1 but my only question is 1-1^2 is 0 wouldn't 0 be lower?

Answer 16

The two end points may not necessarily be the smallest and largest. If it was, that would be too easy of a question.

when x=-4 then y=-15
when x=-3 then y=-8
when x=-2 then y=-3
when x=-1 then y=0
when x=0 then y=1
when x=1 then y=0
when x=2 then y=-3

The largest y value is 1, and the smallest y value in our domain is -15
1-(-15) = 1+15
= 16

Does that make sense to you now?
You're dealing with a quadratic function, the endpoints they give you may not necessarily be the minimum and maximum or whatever

Answer 17

Also just keep in mind, one question per post (:

Answer 18

I do understand now.

Answer 19

Great! :)